|I'm sure Benedict Arnold didn't think of himself as a traitor either. Nor Marcus Brutus or Cassius.|
"The case against Lee begins with the fact that he betrayed his oath to serve the United States. He didn’t need to do it. The late historian Elizabeth Brown Pryor demonstrated that 40 percent of Virginia officers decided to remain with the Union forces, including members of Lee’s family.
As the historian Allen Guelzo emailed me, “He withdrew from the Army and took up arms in a rebellion against the United States.” He could have at least sat out the war. But, Guelzo continues, “he raised his hand against the flag and government he had sworn to defend. This more than fulfills the constitutional definition of treason.”
More germane, while Lee may have opposed slavery in theory he did nothing to eliminate or reduce it in practice. On the contrary, if he’d been successful in the central task of his life, he would have preserved and prolonged it.
Like Lincoln he did not believe African-Americans were yet capable of equality. Unlike Lincoln he accepted the bondage of other human beings with bland complaisance. His wife inherited 196 slaves from her father. Her father’s will (somewhat impractically) said they were to be freed, but Lee didn’t free them.
Lee didn’t enjoy owning slaves, but he was considered a hard taskmaster and he did sell some, breaking up families. Moreover, he supported the institution of slavery as a pillar of Confederate life. He defended the right of Southerners to take their slaves to the Western territories. He fundamentally believed the existence of slavery was, at least for a time, God’s will."
See also: Robert E. Lee's Oedipal Complex